It has been recently proposed that insulin is the link between obesity, hypertension, and glucose intolerance. Both obesity and glucose intolerance are associated with increased insulin resistance, hyperinsulinemia, and increased prevalence of hypertension. In addition, patients with essential hypertension are insulin-resistant and hyperinsulinemic. Therefore, it has been postulated that insulin might play a role in the pathogenesis of hypertension through stimulation of the sympathetic nervous system, promoting renal sodium retention, or affecting cation transport. However, in a cross-sectional study of 2873 Pima Indians seen at the NIH research clinic, there was no relationship between hypertension or blood pressure and serum insulin concentrations. To explore this issue further, the relationship between both insulin resistance and insulin concentrations and blood pressure is being studied in Pima Indians compared to other ethnic groups (Caucasians and Blacks).